natural period of vibration meaning in English

固有振动周期
自振周期

By calculating large quantity of examples , this text studies earthquake resistant behavior of tapered portal frame with pined bases and analyzes its natural frequency , natural period of vibration and vibration mode . by comparing interior forces of pillar top , beam end and span midpoint in two conditions that seismic action effect participates combination of forces and not when portal frame is n ' t changed , ensure conditions that combination of seismic action effect has controlling f unction during tapered portal frame design , and tapered portal frame demands anti - earthquake design
本文通过大量算例分析，研究柱脚铰接楔形变截面门式刚架的抗震性能，并对其自振频率、振型进行了分析；通过比较地震作用效应参与荷载组合与不参与荷载组合两种情况下，梁柱截面尺寸不变时，柱上端、梁端、跨中截面处的内力大小，确定在什么情况下地震作用效应组合起控制作用，变截面门式刚架需要进行抗震设计。